Strange friend request

So I just got a very strange friend request. Dude was level 3 and shown offline. Also there was absolutely nothing on his profile except a badge (6 year old account) and his avatar.

So I accepted, thinking its another bots I can report. However he stayed offline, not even stood there for 5 min in my friendslist and just before I could send a message I got unfriended again, he didn't said or did anything... While I was befriended with him his profile didn't change, didn't show any owned games or inventory items.

I checked my inventory just in case, but nothing was missing.